General Mills has 3 structured interviews that cover 3 sets of competencies: leadership, people and technical. In addition they have a personality test which can raise HR red flags. There is an informal off campus dinner before the day of the interview with hosted breakfast and lunches on campus during the day of the interview when they show you around campus and answer your questions. These informal meals are not interviews but the host is evaluating the candidate and may raise concerns if they come up. The day concludes with HR where they cover benefits, that piece is just a quick overview so the offer is understood if extended.
The biggest challenge is adjusting to answer questions differently based on the interview type you are in. If the interviewer's title is Director, its probably the leadership interview. The technical interview will be obvious, the People interview will be the remaining session. Also, adjusting to be fake informal during the meals is important. Pretend to let your gaurd down but never actually do it.